2,5-dichlorothiazolo(5,4-d)thiazole and process for preparing same

ABSTRACT

2,5-DICHLOROTHIAZOLO(5,4-D) THIAZOLE HAVING INSECTICIDAL PROPERTIES OF THE FORMULA:   2,5-DI(CL-)-THIAZOLO(5,4-D)THIAZOLE   IS PREPARED BY REACTINT TETRACHLOROETHYLENE-BIS-(ISOCYANIDE DICHLORIDE) HAVING THE FORMULA:   C(-CL)2=N-C(-CL)2-C(-CL)2-N=C(-CL)2   WITH AT LEAST THE STOICHIOMETRICALLY NECESSARY QUANTITY OF SULPHUR AT A TEMPERATURE IN THE RANGE OF FROM 150* TO 350*C.

United States Patent US. Cl. 260-306.8 F 3 Claims ABSTRACT OF THEDISCLOSURE 2,5-dichlorothiazolo[5,4-d] thiazole having insecticidalproperties of the formula:

is prepared by reacting tetrachloroethylene-bis-(isocyanide dichloride)having the formula:

with at least the stoichiometrically necessary quantity of sulphur at atemperature in the range of from 150 to 350 C.

This invention relates to the new compound 2,5-dichlo rothiazolo [5,4-d]thiazole, and to a process for its production.

SUM-MARY It has been found that 2,5-dichlorothiazolo [5,4-d]

thiazole, corresponding to the formula (1):

can be obtained by reacting tetrachloroethylene-bis-(isocyanidedichloride) corresponding to the formula (II):

with at least the stoichiometrically necessary quantity of sulphur at atemperature in the range of from 150 to 350 C.

DESCRIPTION The reaction is preferably carried out at a temperature inthe range of from 180 to 280 C.

The process is illustrated with reference to the following example:

In general, at least 8 mols of sulphur are used per mol of the compoundcorresponding to formula (II). -It is "ice advantageous to use an excessof from twice to three times the stoichiometrically necessary quantityof sulphur. In this case, the excess sulphur may optionally be returnedto the reaction circuit. Working with less than 8 mols of sulphur permol of compound ('11) would result in the undesirable formation of acompound with the summation formula C CI N 'S.

The starting compound is known (U.S. Pat. No. 3,251,760).

To carry out the process according to the invention, the startingcompound is mixed with at least the stoichiometrically necessaryquantity of sulphur and the resulting mixture is heated, preferably to atemperature of from 180 to 280 C., until the reaction begins. In onepreferred embodiment of the invention, the sulphur is initiallyintroduced into the reaction vessel and the starting compound (II) isadded to it in portions at the particular reaction temperature, forexample over a period of from 30 minutes to 10 hours, depending on thesize of the batch. The reaction can be carried out in an Open or in aclosed vessel. When the reaction is carried out in a closed vessel, forexample an autoclave or a bomb tube, the starting components are heatedto a temperature in the aforementioned range and, after cooling, thedisulphur dichloride formed is separated off (together with a smallerquantity of sulphur dichloride), for example by fractional distillation.However, the crude mixture can also be treated, for example with water,and the sulphur formed is then filtered olf together with the reactionproduct corresponding to formula (I). The residue is dried and thesulphur is separated off from the reaction product (I), for example bydissolving in carbon disulphide.

When the reaction is carried out in an open vessel, it is best tocontinuously distil olf the sulphur chlorides formed in order to be ableto keep the reaction temperature at the required level and, hence, toobtain as complete a conversion as possible. The reaction is completewhen no more significant quantities of sulphur chlorides distil over.The reaction time generally amounts to between 30 minutes and 10 hours,depending upon the size of the batch.

The process is generally carried out in the absence of solvents,although it can also be carried out in the presence of an organicsolvent which boils at a temperature in the range used and which isinert towards the reactants, for example, 1,2,4-trichlorobenzene,naphthalene, a methylnaphthalene, acen-aphthylene or similar compounds.The process can, of course, also be carried out continuously.

The new dichlorothiazolothiazole corresponding to formula (I) obtainedby the process according to the invention can be used for the productionof plant protection agents, although it does itself have insecticidalproperties. These are illustrated in the following test.

Drosophila test:

Solvent: 3 parts by weight of dimethyl formamide Emulsi fier: 1 part byweight of alkylaryl polyglycol ether.

To prepare a suitable active substance preparation, 1 part by weight ofthe active substance is mixed with the specified quantity of solventcontaining the specified quantity of emulsifier and the concentrate isdiluted with water to the required concentration.

1 cc. of the active substance preparation is pipetted onto a circularfilter paper 7 cm. in diameter. The [filter paper is placed wet on aglass dish containing 50 dew flies (Drosophila melanogaster) and coveredwith a glass pate.

The mortality rate in percent is measured after the interval specified.means that all the flies were killed, 0% means that no flies werekilled.

The active substance, active substance concentration, evaluation periodand mortality rate are set out in Table (LI):

1 After 4 days.- 2 After 3 days.

EXAMPLE 1 512 g. (16 mols) of sulphur are placed in a threenecked flaskequipped with a stirrer, thermometer and distillation bridge, which isthen placed in a metal bath at a temperature of from 245 to 250 C. 360g. (1 mol) of 'tetrachloroethylene bis (isocyanide dichloride) are thenadded in portions in the absence of air over a period of 3 hours. Theportions added should be measured in such a way that the internaltemperature does not fall below 235 C. On completion of the addition,the mixture is kept at the bath temperature of from 245 to 250 C. for 30minutes. After cooling, the residual sulphur chlorides are initiallydistilled oif on a boiling water bath under a Water-jet vacuum. This isfollowed by fractionation in an oil pump vacuum (0.5 Torr) at atemperature gradually increasing up to a metal bath temperature of 250C. and then quickly (over 15 minutes) up to 300 C. Most of the excesssulphur is left in the residue. The distillate solidifying in thereceiver is recrystallised from washing spirit. A little sulphur whichcrystallises out with the distillate is dissolved in carbontetrachloride. 2,5-dich'loro-thiazolo [5,4-d] thiazole corresponding tothe formula I) is obtained in a yield of 62 g. (29.4% of thetheoretical), rn.p. 171 to 172 C. The compound shows a highlycharacteristic infrared spectrum with sharp bands at 1410, 1287, 1071,889, 495 and 398 cmr The sulphur chlorides which distill off quicklyover the bridge during the reaction take appreciable quantities of thethiazolothiazole with them. Redistillation of the sulphur chlorides in acolumn leaves behind a residue which, after suitable working up, yieldsanother 16 g. of pure 2,5-dichlorothiazolo [5,4-d] thiazole, bringingthe total yield to 37% of the theoretical.

4 EXAMPLE 2 The procedure is as in Example 1, except that the metal bathtemperature is kept at 280 C. The total yield after working up as inExample 1 is 4 8 g. (22.8% of the theoretical) of 2,5-dichlorothiazolo[5,4-d] thiazole.

EXAMPLE 3 The procedure is as in Example 1, except that only 256 g. (8mols) of sulphur are used. The total yield is 56 g. (26.5% of thetheoretical) of 2,5-dichlorothiazo10 [5,4-d] thiazole.

EXAMPLE 4 360 g. (1 mol) of tetrachloroethylene-bis-(isocyanidedichloride) and 256 g. (8 mols) of sulphur are mixed and reacted for 3hours over a metal bath at a temperature of 240 C. in an apparatus ofthe kind described in Example 1. Working up as described in Example 1gives 42.5 g. (20.1% of the theoretical) of 2,5-dichlorothiazolo [5,4-d]thiazole.

What we claim is:

1. 2,5-dichlorothiazolo [5,4-d] thiazole having the S 2. Process forpreparing 2,5-dichlorothiazolo [5,4 d]- thiazole which comprisesreacting tetrachloroethylenebis (isocyanide dichloride) having theformula:

References Cited UNITED STATES PATENTS 3,282,951 11/1966 Spivack et al.260--306.8 F

FOREIGN PATENTS 2,009,253 '1/ 1970 France 260306.'8 F

RICHARD J. GALLAQGI-I'ER, Primary Examiner U.S. Cl. XJR. 424-270 UNlTEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,829,435Dated 'August 13 1974 n g fl Gunther Beck and Hans Holtschmidt It iscertified that error eppeara in the above-identified patent and the:said Letters Patent are'hereby corrected as shown below:

Colufim 4; line 25 (Claim formula) D should be si ned and sealed this19th day of November 1974.

(SEAL) Attest: McCOY M. GIBSON JR. I -c MARSHALL DANN Atte'sting'Officer Commissioner of Patents USCOMM DC 00370-90.

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